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A225185 Primes p which do not have a primitive root that divides p+1. 1
7, 23, 31, 43, 47, 71, 73, 79, 103, 127, 151, 157, 167, 191, 193, 199, 223, 239, 241, 263, 271, 277, 283, 311, 313, 331, 337, 359, 367, 383, 397, 409, 431, 439, 457, 463, 479, 487, 503, 571, 577, 599, 607, 631, 647, 673, 691, 719, 727, 733, 739, 743, 751, 811, 823, 839, 863, 887, 911, 919, 967, 983, 991, 997 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

REFERENCES

Arto Lepistö, Francesco Pappalardi and Kalle Saari. Transposition Invariant Words. Theoret. Comput. Sci., 380(3), 377-387, 2007; doi: 10.1016/j.tcs.2007.03.029

LINKS

Table of n, a(n) for n=1..64.

EXAMPLE

The primitive roots modulo 97 are 5, 7, 10, 13, 14, 15, 17, 21, 23, 26, 29, 37, 38, 39, ..., and 7 divides 98, so 97 is not a member of this sequence.

PROG

(PARI) forprime(p=2, 1000, i=0; fordiv(p+1, X, if(znorder(Mod(X, p))==eulerphi(p), i=1)); if(i==0, print1(p", "))) \\ V. Raman, May 04 2012

(MAGMA) [p: p in PrimesUpTo(1000) | not exists{r: r in [1..p-1] | IsPrimitive(r, p) and IsZero((p+1) mod r)}]; // Bruno Berselli, May 10 2013

CROSSREFS

Cf. A060749, A225184 (complement), A001122.

Sequence in context: A044449 A095087 A144517 * A091531 A036259 A004628

Adjacent sequences:  A225182 A225183 A225184 * A225186 A225187 A225188

KEYWORD

nonn

AUTHOR

N. J. A. Sloane, May 04 2013

EXTENSIONS

More terms from V. Raman, May 04 2013

STATUS

approved

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Last modified June 15 04:47 EDT 2021. Contains 345043 sequences. (Running on oeis4.)